package com.tender.utils;

import lombok.Cleanup;
import lombok.extern.slf4j.Slf4j;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Objects;
import java.util.Random;

/**
 * 图形验证码
 */
@Slf4j
public class PicCodeUtil {
    /**
     * 放到session中的key
     */
    public static final String PIC_RANDOM_CODE_KEY = "PIC_RANDOM_CODE_KEY";
    private Random random = new Random();
    /**
     * 随机产生的字符串
     */
    private final String RAND_STRING = "abcdfhjkmnpqrstuvwxyz245678ABCDEFGHJKMNPQRSTUVWXYZ";
    /**
     * 图片宽
     */
    private int width = 110;
    /**
     * 图片高
     */
    private int height = 40;
    /**
     * 干扰线数量
     */
    private int lineSize = 0;
    /**
     * 随机产生字符数量
     */
    private int stringNum = 4;

    /**
     * 获得字体
     */
    private Font getFont() {
        return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
    }

    /**
     * 获得颜色
     */
    private Color getRandColor(int fc, int bc) {
        if (fc > 255) {
            fc = 255;
        }
        if (bc > 255) {
            bc = 255;
        }
        int r = fc + random.nextInt(bc - fc - 16);
        int g = fc + random.nextInt(bc - fc - 14);
        int b = fc + random.nextInt(bc - fc - 18);
        return new Color(r, g, b);
    }

    /**
     * 生成随机图片
     */
    public String getPicCode(HttpServletResponse response, Integer stringLength) {
        try {
            HttpSession session = ServletUtils.getSession();
            //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
            BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
            //产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
            Graphics g = image.getGraphics();
            g.fillRect(0, 0, width, height);
            g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 28));
            g.setColor(getRandColor(110, 133));
            //绘制干扰线
            for (int i = 0; i <= lineSize; i++) {
                drowLine(g);
            }
            //绘制随机字符
            String randomString = "";
            if (Objects.nonNull(stringLength)) {
                stringNum = stringLength;
            }
            for (int i = 1; i <= stringNum; i++) {
                randomString = drowString(g, randomString, i);
            }
            session.removeAttribute(PIC_RANDOM_CODE_KEY);
            session.setAttribute(PIC_RANDOM_CODE_KEY, randomString);

            log.info("后台代码{}", randomString);
            g.dispose();
            @Cleanup ServletOutputStream outputStream = response.getOutputStream();
            //将内存中的图片通过流动形式输出到客户端
            ImageIO.write(image, "JPEG", outputStream);
            return randomString;
        } catch (Exception e) {
            e.getStackTrace();
        }
        return "";
    }

    /**
     * 绘制字符串
     */
    private String drowString(Graphics g, String randomString, int i) {
        g.setFont(getFont());
        g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));
        String rand = String.valueOf(getRandomString(random.nextInt(RAND_STRING.length())));
        randomString += rand;
        g.translate(random.nextInt(5), random.nextInt(5));
        g.drawString(rand, 20 * i, 22);
        return randomString;
    }

    /**
     * 绘制干扰线
     */
    private void drowLine(Graphics g) {
        int x = random.nextInt(width);
        int y = random.nextInt(height);
        int xl = random.nextInt(13);
        int yl = random.nextInt(15);
        g.drawLine(x, y, x + xl, y + yl);
    }

    /**
     * 获取随机的字符
     */
    public String getRandomString(int num) {
        return String.valueOf(RAND_STRING.charAt(num));
    }

}
